This invention relates to air-cooled converter assemblies employing disc thyristors in general, and more particularly, to an improved arrangement which permits arranging the disc thyristors such that they are essentially parallel to the front surface of the arrangement.
Air-cooled converter assemblies using disc thyristors have previously been developed. For example, in British Pat. No. 992,442, a plurality of disc thyristors are clamped together between heat sinks arranged in tandem. The power connections are made using terminal lugs on the conducting heat sinks. Because of the nature of the design, the disc thyristors are parallel to each other with their contact surfaces and all contact surfaces are at right angles to the front surface of the converter assembly. Clearly, this does not lead to ease of connection and requires large amounts of space.
Also previously known are liquid-cooled converter assemblies employing disc thyristors in which are individually clamped and arranted with their contact surfaces parallel to the front surface of the arrangement. An example of such a device is that disclosed in German Offenlegungsschrift No. 1,924,011. This type of design, with the disc thyristor surfaces parallel to the front surface and which has not been heretofore common in air-cooled converter assemblies is possible since, with liquid-cooled disc cells, heat sinks required are not as large as those required for air-cooled operation. A typical design of an air-cooled converter assembly using the thyristors arrangement of German Offenlegungsschrift No. 1,924,011 is disclosed in detail in German Offenlegungsschrift No. 1,913,546. From the arrangement disclosed therein, it is evident that the juxtaposition of large heat sinks results in a bulky design. Furthermore, from this disclosure, it is obvious that only threaded-stud thyristors with ratings smaller than those typically found in disc thyristors can be conveniently used. Using disc thyristors in this type of design would require even larger heat sinks and thus, more space.
Thus, there is a need for an air-cooled converter assembly employing disc thyristors which includes heat sinks which are large enough to dissipate the heat produced by the thyristors and at the same time are arranged in a space saving design.